It usually means that you are looking at a web site with incomplete information. The "price" they show is sometimes the amount owed, to a Home Owner Association, for example. The HOA has filed to foreclose due to unpaid fees. If you "buy" the home at foreclosure auction for that amount, you buy it "subject to" senior liens. Often they are higher than the home is worth. Surprise! If it has existing tax liens, they might become yours.
I get asked every day about deep discount homes, nice looking homes priced @ 10% of apparent market value, or so. In each market, there are dozens of folks who have the latest tools to spot real bargains before they ever get published. They get up early and scour the market each day for such bargains. When they find one, they verify the information from multiple sources, and do a drive by on the ones with potential. They snap them up before you and I ever even hear of them.
So, ask yourself, am I equipped to compete with those folks, by equipment and tools, education and temperament? If there were such a bargain publicly advertised, wouldn't someone have already bought it? If you really want to play in that arena, find yourself a mentor, someone who knows the pitfalls, understands the questions to ask, and is willing to teach you the game. Learn carefully and slowly. Then go get 'em.